User`s manual
79
FX3U Series Programmable Controllers
User’s Manual - MODBUS Serial Communication Edition
8 Master Specification
8.2 FNC 276 - MODBUS Read/Write Instruction
1
Outline
2
Specifications
3
System
Configuration
4
Wiring
5
Communication
Setup
6
Related
Devices and
Comm. Status
7
MODBUS
Standard
Commands
8
Master
Specification
9
Slave
Specification
10
Creating
Programs
8.2 FNC 276 - MODBUS Read/Write Instruction
8.2.1 Outline
This instruction allows the MODBUS Master to communicate (read/write data) with its associated Slaves.
1) Instruction Format
2) Set Data
3) Applicable Devices
8.2.2 Explanation of function and operation
1) 16-bit operation (ADPRW)
Command Code
is operated on Slave Node according to Parameters , ,
and / .
Use 0 as the Slave Node Address for Broadcast commands.
Operand Type Description Data Type
Slave Node Address 16-bit binary
Command Code 16-bit binary
Command Parameter depending on the Command Code (See Section 8.3) 16-bit binary
Command Parameter depending on the Command Code (See Section 8.3) 16-bit binary
/
Command Parameter depending on the Command Code (See Section 8.3) Bit or 16-bit binary
Operand Type
Bit Devices Word Devices Others
System User Digit Specification System User
Special
Unit
Index
Con-
stant
Real
Number
Charac-
ter String
Pointer
XYMTCSD
.b KnX KnY KnM KnS T C D R
U\G
VZModifyKH E "
"P
33 3 33
33 3 33
33 3 33
33 3 33
/
333 3 3 3 3 3 3
FNC 276
ADPRW
Mnemonic Operation Condition
32-bit Instruction
16-bit Instruction
11 steps ADPRW
Mnemonic Operation Condition
Continuous
Operation
S
S
1
S
2
S
3
S
4
D
S
S
1
S
2
S
3
S
4
D
S
1
S
S
2
S
3
S4
D
Command
input
(normally ON)
FNC276
ADPRW
S
Slave
Node
Address
Command
code
/
Command Code
Parameters
Command Parameters
depending on the
Command Code
(See Section 8.3)
Command Code
(See Section 8.3)
Slave Node Address
00H to 10H (0 to 16)
S1
S2
S3
S4
D